Stabilized mineral oil composition



cussed above is well known. Since the action of these inhibiting materials is apparently catalytic, the problem of their development is a difficultone and is evidently influenced to a large degree by the oxidizable constituents which are in the oil following a particular refining treatment. Thus, a particular inhibitor or. class of inhibitors may be effective to stabilize a highly refined oil against acid formation while the same inhibitor may have no appreciable effect upon acid, color or sludge formation in a moderately refined oil and vice versa. This same inhibitor may or may not be effective in inhibiting acid, sludge and i' color formation in a solvent-refined oil and 4may or may not be effective to inhibit the corrosive action of a solvent-refined oil toward metals such as used in cadmium-silver bearings.

One of the principal features of the compounds or class of compounds contemplated by this invention resides in their property of acting as a negative catalyst toward the oxidation of highly rened oils, solvent-refined oils and moderately reiinedoils.

This invention is predicated upon the discovery that the reaction product obtained by reacting an alkali metal mercaptide, or, more specifi` cally, an alkaline solution of a mercaptan with beta-beta-dichlor diethyl ether, possesses the property of acting as a negative catalyst toward the oxidation of viscous oils of the highly refined, moderately reflned-and solvent-refined" types. The general reaction just referred to, whereby the compounds contemplated herein are formed, may be illustrated by the following equation:

Fifty-six grams (one mole) of potassium hydroxlde were dissolved in 250 cc. of ethyl alcohol and 104 grams (one mole) of amyl mercaptan were added to the'solution. The solutionwas then refluxed and 70 grams (appproximately 0.5

mole) of beta-beta-dichlor diethyl ether were slowly added. The precipitate of KCl was filtered off and the filtrate added to water. The oil layer formed was separated and distilled under reduced pressure, the desired product being collected between the temperatures of 160 and 185'C. at 5 mm. pressure. Thev product obtained by the foregoing procedure is the prod-` uct herein referred to as diamylmercaptyl di.- ethyl ether. y

EXAMPLE Two Eleven grams (0.1 mole) of thiophenol (phenyl mercaptan) lwhere dissolved in 100 co.v of ethyl alcohol containing five grams of NaOH. This solution was heated to refiuxtemperature and 7.1 grams (0.05 mole) of Ybeta-beta-dichlor diethyl Special proce-V ether were added slowly thereto and upon completion of the reaction the mixture was poured into water and the insoluble layer was separated and distilled under reduced pressure, the fraction boiling between 190 and 200 C. at 5 mm. pressure being recovered as diphenyl mercaptyl diethyl ether. 'Ihe product on standing gave a solid having a melting point of 65 C.

The effectiveness of the compounds contemplated herein as antioxidants for mineral oll fractions is shown by the following examples:

EXAMPLE A (Highly refined oils) The test used to demonstrate the antioxidant effect of the compounds contemplated herein upon highly refined oils was a modified German tartest which involved heating a 150 gram sample of the oil to a temperature of 120 C. and bubbling oxygen gas1 through the sample for a periodof 70 hours. At the end of this test the acidic oxidation products formed in the oil `were determined by titrating with caustic alkali, and the results are recorded in the terms of neutralization number, which represents the number of milligrams of KOH required to neutralize the acids-formed in one gram of oil. The oil used was ofv the highly refined type, suitable for use in transformers and the like, which had been obtained from a Coastal distillate by successive treatments with 40 lbs. per bbl. of 98 per cent sulfuric acid and 180 lbs. per bbl. of 103 per cent oleum, followed by neutralization, washing and clay percolation. 'I'he oil had a specific gravity of 0.87,A a flash point of 310 F., a Lovibond color of less than 0.1 and a Saybolt Universal Viscosity of 69 seconds at 100 F. The results obtained in this test, using the oil alone and the oil blended with respresentative dimercaptyl diethyl ethers are indicated in Table I below;

Table I Neutralization l number after test Oil alone 25.00

0il+.10% diamyl mercaptyl diethyl ether- 0.04

Oil-|-.10% diphenyl mercaptyl diethyl ether 0.02

EXAMPLE B Moderately refined oil For testing moderately refined oils a sample of oil was heated to 110 C. in air for a period oi.' '72 hours in the presence of apiece of copper foil, after which the color and neutralization number (acidity) of the oil was noted. The oil used in demonstrating the effect of the compounds contemplated herein was an oil, suitable for-use in turbines, obtained from* a blend of 92 per cent Midcontinent distillate and 8 per cent Coastal distillate by treatment with 'l0 lbs. per bbl. of 98 per cent sulfuric acid, followed by neutralization, washing and clay percolation. This oil had a specific gravity of 0.879, a ash point of 385I F. and a Saybolt viscosity of 152 seconds at 100 F. The results of the test on this oil, using representative dimercaptyl diethyl ethers, are given in Table II below.

amaai l treatment, tsja faetorfeirecting its' charateristis., `It is possible; for example.` by selection` oflthe' vIt will be observed from the `foregoing results a slight reduction in acid formation, but it gave van appreciablereduction in color formation;y and tha'tr the diphenyl mer'aptyl diethyl ethergave and acid. i w EXAMPLE C i (Sozvent-'refineaoilsi oils have a tendency, when exposed to theconbearing metals. To determine the'eiectiveness f of the compounds contemplated-herein as inhibitors of such corrosive action ina-fsolventrened oil the following test was use dr'A Y silver alloyjsurface and weighing'about '6.0 grams was placed in 30 ygramsfoffthe' motor'oil .sample "l 22 hoursvvhile a streamfof airwas bubbled f mentis anl indication o f the extent to *whichl corr' rosion has taken place. The oil used in..,thi s n l had a specicl gravity of 0.8,72, a"ash point of 1o,0,F.x Y.

The .results listed in .Table .IIIjbelow were vob- Oil al0ne aa v il .25%'diamyl mercaptyl diethyl ether-- 50 Oil .10% diainyl'I riercap'tyl diethylethe'ri- 85 Oil .10% diphenyl'mercaptyl diethyl ether `2 vr'Oil .05% diph'enyl mercaptyl diethylaether" 0 .'fIt will be observed from 'the/foregoing results l i' oxidation' in mineralv oil fractions yof the highly Qnsolventrefined'- asused herein are not neces- "'sarily confined to oils obtainedjbyfspecifie meth-j .hlibitor response similar;- to the illustrative oils is againgpointed'out that the' cr ude stock from that the 'diamyl mercaptyl diethyl ether gave only veryv good stabilization in respecttoboth colorf As has been noted above, solvent-refinedvmotor ditions rtvithinan internal combustion f engine crankcase, to' corrode materially certain alloy -f Asection of a bearing containing 'a cadmium-' against the surface of the metal specimen. The loss inweight of thebearing during-this treat-* Y- test wasg'amotoroil (f S. A. 20),obtained frox'n 0 'a Pennsylvania..mixed--ineutral rresiduuIn-stock- ,f solvent-refined by` extraction Ywith chlorexg it 1 435'? F. and a Sayboltvis'cosity of 3 18 seconds at;

fta'ined Ywith the oil just described above' vvhen=` testedlalone andw'ith the laddition of 'different famounts-of dimercaptyl diethyl ethers,.-.In'each jrfcasev atsample' of the' 'oil containingl a stabilizer rWas run at) the, sametilnefasia samplej'ofthev o'f thebearingin theunstabilizedoil gives the'per` 011v .01% -diphenyi-'mercaptyi methyl ether'v 494 v that thejdimercaptyl Ac iiethyl.ethers pros'sessthe"v if iproperty of inhibiting the' deleterious eilectsofy Qrened',.inoderately. reiined, andV solvent-reiined f f types.y It .is tobejunderstood;however,that the f yterms ,highly rened,moderately refined," and.

Y'jcentto about 1.0per'eent.

8.'.-mproved' mineral oilcompositionbom? f prisinga` viscous mineraloil fraction havinginf admixture therewith diamyl mercaptyljdiethyl about 0.01 perff'j odsof renng but are intended as indcalti ve of "oils vlfiaving deterioration V clraraeteristics and in- I 'given in the examples above; .@Inthisf'regard it/ y y icenttoabout 1 .0peree1 1`t. i .1; L whichtheoilis obtained;aswellasthe1ferining yv T f' i ROBERTO.

4 Would'yield .aV moderately refined 4oil from an other crude stock.`

The `amount of'v the y'compound used .maybe Y 'varied dependinguponthe type of 'oil' frz'icti'onv With which it is blended andthe conditionsunder which itis used. In general-it appears-'thatfthe compounds contemplatedherein can be used i1 i`f v,amounts ranging Afrom 0.01 per cent YtoLOO .per

cent with amounts'ran'ging from 0.05 per centto '1 0.50 per cent giving satisfactory results; Y

llclaim:v

1. vAnimprovedmineraly oil co'i'mtiosition"oom-k @prising aviscousmineralgfoil fraction'havin'g in admixture therewith a minor proportion of a dif; IV

mercaptyl diethyl etherfin an amount suiicient to inhibit the ,deleteriousv effect of oxidationon ntheoii. f to bev tested.. The'oil Wasgheated to 175 C; for

`2. 'Anf improved mineral oil composition" Home prising a viscous mineralfoil fraction-having .in l I admixturetherewith a` minor proportionago'f 'al R's-czni-ocim-#saj in -vvhiclfi'lftv represents a. radical selectedffrom the group consistingof alkyl.l aryl`,faralkyl and:l falkaryl'radicals, saidA compound being' present in I an amount sufficient to inhibit the deleterious''efv fects of oxidation on the oil.

improved'mineral foil compositionsoorzi-f j prising a viscous nriineralfoil fractionhaving in admixture therewith a minorproportionof af ditionon the oil.

'4 2 A n improved .mineral oil compositiori mimiprising ag'visoous mineral oil kfraction havinglin admixture" therevvitlna` minor yproportion of a' 5. An improved mineral oil composition coxn-L Aprisinga viscous mineral oil .fraction havil'ig'aLdfV mixed therewith in the proportion? of from about 0.01per c`ent to about 1.0'p`er cent a dimercaptylr diethyl ether.

6. Ari i improved mineral oil *composition Y com prising al viscous mineral oil fraction having in? admixture ,therewith a minor proportion; of "a-,L

`35:;` Y?. alkylrnercaptyl diethyl ether inanamount sful-` 'cientto inhibit the'deleterious effects ofoxida-f compound selected from the-group con'sistingof u diamyl mercaptyl`.diethyl ether( and diphenyl;r 'mercaptyl diethyl ether, saidcompoundjbeing 1' present inthe oil in YVan amount sufiicientto inmbit the deieteriouseffects ofL oxidation onfth'el oil. Y

7. An improved mineraloil' composition-"com-jV ,prisingfa viscous mineral'oil fractionhaving 'in admixture therewithI diphenyl merc'aptyldiethyl j ether in the! proportiony of 1 .from about 50.01 Loper,

ether intheproportion of. from 

